"Rodgers has a shoulder injury," McCarthy said. "They want to run more tests. They don't have an exact diagnosis."

Rodgers appeared ready to shrug off the injury, playing toss with backup Seneca Wallace on the sideline. Shortly thereafter, he jogged to the locker room for testing.

It wasn't a good sign when the team doctor returned to the sideline without Rodgers later in the first quarter. The fear is that the injury will be diagnosed as a collarbone fracture as opposed to the type of AC joint separation that Tom Brady played through in the 2011 playoffs.

Rodgers has been as valuable as any player in the league this season, keeping his team in first place in the NFC North despite a series of injuries to key players on both sides of the ball.

With a suddenly dominant ground attack, the Packers, who also lost starting guard T.J. Lang for the game to a concussion, can withstand a short-term absence from Rodgers. If he's forced to miss a month or more, though, they could fall behind the Bears and Lions in a tight division race.

Although Wallace has taken over as the starting quarterback, don't be surprised if the Packers put in a waiver claim on Matt Flynn -- released Monday by the Buffalo Bills -- or place a phone call to Vince Young. Desperate times call for desperate measures.